1. Field Of The Invention
The present invention relates to power driven rotary saws and more particularly to an improved blade guard system for power driven circular cutting wheels wherein the cutting wheel is changed from a relative inboard position to a relative outboard position.
2. Description Of The Prior Art
Traditionally rotary saws such as portable power driven circular saws are provided with a blade guard or protective cover for the circular cutting wheel or blade. For convenience the cutting wheel, whatever its form, is herein after referred to as the saw blade or blade. In such prior art devices the blade guard is attached to the saw shaft and provides for limited forward and backward rotational movement relative to the blade to achieve limited desirable protective positions.
For some cutting operations it is desirable to mount the saw blade inboard, for center cutting, for example, and in other operations it is desirable to mount the saw blade in the outboard position, for flush cutting, for example. Generally it can be said that when mounted on the inboard position, the saw blade is approximately in a vertical plane passing through the center of gravity of the motor assembly. When mounted on the outboard position, the saw blade is on the outboard side of the supporting arm and in position for cutting close to an obstruction. In some prior art devices, when changing between inboard and outboard cutting positions, it is necessary to remove the saw blade, blade guard or belt guard from the saw shaft and reattach in the new position. In the prior art device the blade guard is provided with a track slot or slots substantially adjacent the saw shaft for adjustment of the blade guard to forward and rearward positions to increase protection of the operator. Such track slots were generally releasably attached directly to the main drive shaft arm as associated belt guard devices. Such prior art arrangements have resulted in early fatigue failure of the blade guard.
In U.S. Pat. No. 3,518,888 there is disclosed a circular saw which is constructed so that the circular saw blade can be removed from the saw blade shaft and remounted on the other end of the shaft to provide selective mounting on either end of the shaft. The saw blade cover is also removed at the same time.
While such prior art devices have provided improvement in the area intended, there still exists a great need for a blade guard system which eliminates the need to remove the saw blade, blade guard or belt guard when changing between inboard and outboard blade positions. There is also a need to provide a blade guard system having improved resistance to fatigue failure.
Accordingly a principal desirable object of the present invention is to provide an improved blade guard system for rotary saws which eliminates the need for removing the saw blade and blade guard when changing between inboard and outboard saw cutting positions.
Another desirable object of the invention is to provide a blade guard system for rotary saws which is constructed and arranged so that during adjustment of the guard the guard is prevented from inadvertently rotating to a position where the operator is exposed to the blade.
Another desirable object of the present invention is to provide a blade guard system having improved resistance to fatigue failure.
A still further desirable object of the present invention is to provide a blade guard adjustment arm which is located in the same relative position for inboard or outboard blade cutting positions.
Another desirable object of the present invention is to provide a blade guard adjustment arm which provides for improved assessability of adjustment.
These and other desirable objects of the invention will in part appear hereinafter and will in part become apparent after consideration of the specification with reference to the accompanying drawings.